make importSuites work with jscover

jscover, unlike jscoverage puts another entry into the suites export which
obviously fails the suit run.

bin/vows

@@ -567,23 +567,27 @@ function importSuites(files) {
     } : function (suites, f) {
         //f = path.join(process.cwd(), path.relative(process.cwd(),f));
         var obj = require(f);
-        return suites.concat(Object.keys(obj).map(function (s) {
-            try {
-                obj[s]._filename = cwdname(f);
-            } catch (e) {
-                if (e instanceof TypeError && typeof(obj[s]) === 'undefined') {
-                    abort("runner",
-                          "Caught a TypeError while trying to import " +
-                          "suites: a suite is undefined." +
-                          "Check your exports; are you doing something like " +
-                          "exports.suite = vows.describe('foo')." +
-                          "addBatch({}).run()? If so, remove '.run()'");
-                } else {
-                    throw e;
-                }
-            }
-            return obj[s];
-        }));
+        return suites.concat(
+            Object.keys(obj)
+                .filter(function(s) { return s !== '_$jscoverage'; })
+                .map(function (s) {
+                    try {
+                        obj[s]._filename = cwdname(f);
+                    } catch (e) {
+                        if (e instanceof TypeError && typeof(obj[s]) === 'undefined') {
+                            abort("runner",
+                                  "Caught a TypeError while trying to import " +
+                                  "suites: a suite is undefined." +
+                                  "Check your exports; are you doing something like " +
+                                  "exports.suite = vows.describe('foo')." +
+                                  "addBatch({}).run()? If so, remove '.run()'");
+                        } else {
+                            throw e;
+                        }
+                    }
+                    return obj[s];
+                })
+        );
     }, [])
 }